Polychlorinated biphenyls are extremely useful materials and are widely used as insulators and in heat exchangers. However, they are also almost indestructible by the environment and when present in water bodies concentrate in the tissue of fish, and can have an adverse effect on humans eating the fish.
Procedures to dispose of PCB's have been sought and the only procedure which has been practised to any degree is to burn the PCB's at high temperature. This procedure is unsatisfactory since potentially toxic gases are produced, complete combustion must be effected to prevent PCB escape and destruction of otherwise potentially-valuable material associated with the PCB's also occurs.